The present invention relates to aircraft and more specifically, but not exclusively, to passenger aircraft with wing tip devices.
There is a trend towards increasingly large passenger aircraft, for which it is desirable to have correspondingly large wing spans. However, the maximum aircraft span is effectively limited by airport operating rules which govern various clearances required when manoeuvring around the airport (such as the span and/or ground clearance required for gate entry and safe taxiway usage).
In some suggested designs, aircraft are provided with wing tip devices which may be folded to reduce the span of the aircraft on the ground (compared to when the aircraft is configured for flight). The wing tip devices may, for example, be configurable between: (i) a flight configuration for use during flight and (ii) a ground configuration for use during ground-based operations, in which ground configuration the wing tip device is moved away from the flight configuration such that the span of the aircraft is reduced.
It may be desirable for the movement between the flight and the ground configurations to comprise both a rotational component of movement of the wing tip device, and a translational component of movement of the wing tip device relative to the wing. The rotational movement typically allows the wing tip device to be rotated upwards or downwards to reduce the span of the aircraft, whereas the translational component may, for example, enable the wing tip device to disengage from a locking arrangement.
There are technical challenges in providing a practical arrangement for providing such movement. Amongst the issues to be addressed are: the problem of providing a safe and reliable arrangement to enable such movement without impacting unduly on the design of the wing; and the problem of providing a compact and lightweight drive to effect the movement of the wing tip device. The present invention seeks to mitigate at least some of the above-mentioned problems.